INVASIVE PHYTOPHAGOUS PESTS ARISING THROUGH A RECENT TROPICAL EVOLUTIONARY RADIATION: The Bactrocera dorsalis Complex of Fruit Flies

The Bactrocera dorsalis complex of tropical fruit flies (Diptera: Tephritidae: Dacinae) contains 75 described species, largely endemic to Southeast Asia. Within the complex are a small number of polyphagous pests of international significance, including B. dorsalis sensu stricto, B. papayae, B. carambolae, and B. philippinensis. Most species within the complex were described in 1994 and since then substantial research has been undertaken in developing morphological and molecular diagnostic techniques for their recognition. Such techniques can now resolve most taxa adequately. Genetic evidence suggests that the complex has evolved in only the last few million years, and development of a phylogeny of the group is considered a high priority to provide a framework for future evolutionary and ecological studies. As model systems, mating studies on B. dorsalis s.s. and B. cacuminata have substantially advanced our understanding of insect use of plant-derived chemicals for mating, but such studies have not been applied to help resolve the limits of biological species within the complex. Although they are commonly regarded as major pests, there is little published evidence documenting economic losses caused by flies of the B. dorsalis complex. Quantification of economic losses caused by B. dorsalis complex species is urgently needed to prioritize research for quarantine and management. Although they have been documented as invaders, relatively little work has been done on the invasion biology of the complex and this is an area warranting further work.